Television system



Oct. 5, 1937. R. HARDING, JR

TELEVISION SYSTEM Filed Jan. 29, 1934 2 Sheets-Sheet l INVENTOR Ocl:; 5, 1937. R, HARDWG, JR I 2,094,983 I TELEVISION SYSTEM Filed Jan. 29, 1954 1 2 Sheets-Sheet 2 INVENTOR Patented Oct. 5, 1937 UNITED STATES PATENT OFFICE TELEVISION SYSTEM Application January 29, 1934, Serial No. 708,747

8 Claims.

This invention relates to a television system and particularly to one which makes use of moving reflecting surfaces.

One of the objects of the invention is to provide a simple and inexpensive reflecting surface for a television scanning apparatus.

Another object of the invention is to provide a television scanning apparatus in which the parts may be more compact and the reproduced picture brighter.

Another object of the invention is to provide a television scanning apparatus using rotating reflectors with means to position the light source closer to' the reflectors.

Still another object of the invention is to provide a television scanning drum which is less expensive to construct than those heretofore used.

Other objects of the invention and objects relating to the method of constructing the various parts and the assembly thereof will be apparent as the description of the invention proceeds.

Several embodiments of the invention have been illustrated in the accompanying drawings in which:

Fig. 1 is a perspective View of a television receiving apparatus incorporating the invention;

Fig. 2 is a diagrammatical plan View of the arrangement of Fig. 1;

Fig. 3 is a diagrammatical plan view of a known receiving apparatus similar to that of Figs. 1 and 2 but having a different curvature for the reflectors;

Fig. 4 is a diagrammatical plan View of a modifled form' of the invention using the same drum as shown in Fig. 3;

Fig. 5 is a plan view similar to that of Fig. 4 showing a modified means of producing the same result;

Fig. 6 is an enlarged fragmentary perspective view showing a portion of one of the reflectors used in the invention;

Fig. '7 is an enlarged fragmentary view of a modified form of the reflecting surface; and

Figs. 8 and 9 are a plan and a side elevational view, respectively, of two plates showing one way of obtaining the correct angular spacing. Referring now more specifically to the drawings the invention is shown with a helical mirror drum ID mounted on a suitable shaft H driven by a motor l2. A light source [3 is positioned a short distance away from the drum and the reflection of this light is picked up in the drum by the eye M in a manner to be hereinafter described.

The drum I is similar to that described in the application of Arno Zillger, Serial No. 626,579, filed July 30th, 1932. The drum of this application comprises a plurality of plates l (Fig. 3) preferably rectangular in shape and provided with a hole at the center thereof so that a stack of plates may be mounted upon a shaft there being one plate for each line of the picture to be produced. One edge I6 of each'ofthe plates is polished to form a high reflecting surface and the plates are arranged with equal angular spacing around the shaft so as to form a helix which passes once around the shaft; In other words, when the shaft is rotated in front of the eye the reflecting surfaces 'will cross the line of vision in succession each plate passing once for one complete rotation of the shaft.

The light source 13 may be any modulatable source creating a line of light, or any source associated with an optical system for producing the same effect. I prefer to use the gaseous discharge lamp'des'cribed and claimed in the application of John W. McKay,'Serial No. 628,321, filed August 11, 1932, which comprises a pair of spaced apart bulbs I1 and 18 connected by a relatively small diameter tube l9 which is fused to each of the bulbs and forms with them a gas-tight envelope. The bulbs I1 andfl8 may be about-the size of a No. 24 type radio tube and the connecting tube I9 may have an outside diameter of inch. In the bulb I1 I position the. cathode 20 which is preferably formed of a strip of nickel mesh about nine inches long and about an inch wide and wound around a support rod 22 to which one end of the mesh may be "welded. The roll of mesh should not be too tight and may be prevented from unrolling by spot welding the outer edge. The support rod 22 may be welded to another support rod 23 sealed in the press 24 which is formed integral with the bulb, the rod 24 forming the lead-in wire for the lamp. A disc of mica 25 may be positioned at the end of the cathode where it joins the support rod'23'to protect the press from the discharge.

In the bulb I8 is positioned the anode 26 which may be a small nickel cup welded to the top of the support rod 21 sealed in the press 28 of the bulb and forming the anode lead-in wire. A disc 29 of mica may be attached to the support rod between the anode and the press to protect the press similarly to the disc 25 for the cathode.

The lamp l3 may be filled with an ionizable gas such as one of the monotomic gases, neon, argon, helium, krypton, and xenon, and preferably a small amount of metal vapor is mixed with the gas. This metal vapor may bethat of mercury or'one or more of the metals of the alkaline group, The pressure of the gasfshould -be in the neighborhood of 10.. mm. of mercury although this'pressure'i's notcritical. The preferred form of lamp contains about 10 mmj'of neon andasmall drop of mercury and operates [at about/300 volts. with a current of 100 mliamperes r V 7 If such a -lamp is spacedjfrom'the drum ID as shown in Fig. '1 and is modulated in accordance-with the television signal the .reflection of a small portion of the tubular portion 19 of :the

lamp'will appear to an observer who. islooking at.the drum onone of the reflectingsurfaces and as the drum'is; rotated-in a clockwise direc-f j .tion' the sp ot of light will move from 1.3mm right 5 "across the reflecting" surface. Whether-or not;

the observer will see' the. reflection of the. light in one' or more of the reflecting surfaces at any 7 giveneinstant is determined by'the size of the drum, the, distance the light is awayifrom xthe drum..and;,the distance the observerfis away.

from the drum- A;drum 'similar to thatusedin' fthe' above-application. composed of 60" plates; fQaCh h8, V1 ng;3 thickness of th; ofgan inch, 'makingthe total height-of 'theldrum sixiixichesgi V and 'awi'thalengthhqrial to :7.2' inchesjhas its V platesifspacedsix 'degrees' apart.

'With' this arrangement I have foundith at. with the observer ten feet' fr'om' thedrum he will see the lightain.only oneplateata time ifjt he light "is about 48"inchesaway from .the.;drum." Bring ing thelig'htlnearer will cause the observerl'tm see the 'light in more than one surface at the "i same time' and will thus; cause him tofisee a for'e'shortehed pictureand a portioni of another? 7 .-p icture. ";If the light isfpliahed too close he may I see three or four :pictures. ..'I'his positioning of i the lamp is not critical but'the distancehas to be'maintained'in order to get the correct effect;

v Obviously the nearer the light is to the 'drum' the brighter will be the picture" produced and henceone of the objectsof the invention'is to get the-light nearer'to. the drum; This maybe done'by'providing .concavelyfcurved reflecting edges on the plates: instead of straight edges.

1 This construction isshown in Fig. 1 andis illus-* trated diagrammatically in' Fig. 2 where the.

curvedplates30 permit the light to .be moved up '1 tewithin a few inches offthe drum thus gaining :enormously ipicturewith respect to the brightness of the In Fig. '4 another meansis shown to accomplish the same purpose. In this flguretheplates I5 of i the drum are similar to thoseiof Fig. 3' having a:

5 straight edge while a curved mirror 3|is positioned adjacent the drum in the path of light rays- 32, indicated bythe' dot and dash'lines, which would nornially come from the sourceil3 if it' were positioned in the normalplace shown inFig..3. 'I'he-in'irror 3| v is giv'entheproper curvatureso that a light "source 33. positioned adj acent to. it will have its rays bent in the same very much nearer the drumand direction as the rays32'but'the source 33 will' be V V the picture will be therefore very much-brighter. i "In Fig; 5 in place of the mirror 3|.

I 'provide a 'lensf34' "and the" light source is positioned on the opposite side of the lens fromthe drum.

L'I'he curvature of the reflecting edges of the drum shown in Figs. 1 and 2 may be somewhat different from the curvature of the mirror of y-Figi 4-and'thecurvature--01? the lens inFig. 5.

Where'the curvedsurfaces are provided on the drum 1 itself a truly cylindrical. @WVQ may 'be foundsatisfactory. However, the curved mirror 3| of Fig. '4 may be; given a parabolic curve. so

drum rotates. The lens 34 of cylindrical to give the'correct results.

:Moving the'light source nearer to the" by any of the meansdescribed' above has the effect that the distance from the light source to the surface of the drum will'remain constant as the j 1 Fig. 5 may also be of widening the spot of'light picked. upon the reflecting surfaces, To overcome this; I -make the light source smaller in diameter or provide an-aperture to decrease its'width. 1 Such a means.

other'way of cutting. the width of-the light'down 'is'shown in Figs. 1,: 2 and 4, where an opaque mask l8 is provided with a slot 19* just large .enough to give the desired width of light. An

would be to "use a gla'ssrod' 35 about of an 7 inch .in diameterinfr'ont of the light source "as shown in Fig .-5. The rod acts as a lens concen tratingthelight instead of reducing its intensity;

' Inasmuch as'a line; oflight is used with a}re 4 ceiverfof this I naturev to reproduce the. picture the tru'eness of the refiectingsurface in a ver- I tical direction or parallel to theaxis of the drum is not important but; the surface must be very. accurate lengthwise; of Y the 1 plate or; transverse to the. axis; of thejdrum. This is to prevent the light reflection from being-seenin'more than;

one position at a time horizontally g V I have found that the surface, may" be:- comas such irregularities. lie in the. same direction reflecting surface as faras looking'fat the re-. f

flection of some object is concerned. Ifa smooth surface is buffedin'one direction only sothat the bufiing wheel'make's fine scratches 'infone direction" on the surface it will be found to: give good results-without anygrin'ding or lapping.- In Fig.6 a'portion'ofa plate 36 1s shown, the" v edge surface. 31 of which has beenflrst milled.

and thenbufied' so that the fine scratches. .38

lie in one direction and that direction is parallel to'the'sides ofthe plate. 'The effect of such a surface may be to give a dull appearancewhen, looking directly at it and ofcourse there is some absorption; but. as long as'the surface is accu{ rate lengthwise'of the plate the reflection of light from theline source will be correct for producing,

'a television picture.

If desiredthe surface may be provided with ridges of apredeterminedsize which may be cut into the surface witha millin'g machine" or by 7 7 any other method. In Fig. 7a portion .of a plate" 39 is shown with" ridges 40. cut longitudinally." therein. These ridges may then be bufied which will give them a suitable finish for. the purpose.

and 3Tare shown as straight it is understood.

that they may be curved'similar to the edges;

ofthe plate 30 or they may have any other. curvature.

The effect of the particular type of surface on V the plates is to increase the vertical angle of observation of the drum; l In other words the surface made in'this'way tends to diffuse the light 7 vertically or transverse to the plate regardless of the point of observation.

been found necessary to have a light source which is somewhat longer than the height'of the drum '7 so that the reflection of it will not be cut off from thelowermostand uppermost plates when the p While the reflecting surfaces ofthe two plates 36 It has heretofore plates at the proper angle is shown. Here the plate 4| is shown provided at the ends with a downwardly bent tongue 42 and a slot 43 spaced six degrees from it. The tongue 42 engages the slot 43 in the plate immediately beneath it when the plates are at the right angles. The slot and tongue may be accurately put in the ends of the plates in a punch press so that they will all fit together properly with a minimum of assembling effort.

While the invention has been illustrated in connection with television receiving apparatus it is also applicable to television transmitting apparatus in which a light-sensitive cell would be positioned in place of the lamp with means to project an image onto the cell. The invention is, therefore, intended to cover any system either transmitting or receiving in which the light or the light-sensitive cell is brought closer to the drum.

Many modifications of the invention may be resorted to without departing from the spirit thereof and I do not therefore desire to limit myself except as such limitations occur in theappended claims.

What I claim is:

1. A televisiondrum comprising a plurality of stacked plates, each plate having a definite angular relation with those next to it, and protruding means on each plate adapted to engage a portion of a plate next to itto maintain said plates in accurate angular relation.

2. A television drum comprising a plurality of stacked plates, each plate having a definite angular relation with those next to it, a reflecting edge on each of said plates, a member on each plate extending out from the plane of said plate, and means on the plate adjacent to it to engage said member so as to lock each plate to a plate adjacent to it.

3. A television drum comprising a plurality of stacked plates, each plate having a definite angular relation with those next to it, a lug extending out from the plane of each plate at a point spaced from the center thereof, and means on an adjacent plate to engage said lug whereby each of said plates is locked to a plate adjacent to it.

ROBERT HARDING, JR. 

